Seismo-meteo-electromagnetic phenomena observed during a 5-year interval around the 2011 Tohoku earthquake

Publication date: Available online 19 February 2015 Source:Physics and Chemistry of the Earth, Parts A/B/C Author(s): Alexander Schekotov , Masashi Hayakawa The purpose of the paper is to try to find ULF electromagnetic precursors to the 2011 Tohoku earthquake (EQ), on the basis of extensive investigation of radiations in vertical component of the magnetic field or with a large ratio of the vertical to full horizontal component. Nighttime records have been analyzed of three Japanese fluxgate magnetometers located in a distance from 300 to 1300km from the epicenter of the main shock, and the frequency range from 10 to 150mHz was used for the analysis. We have applied wavelet analyses to improve the detection of pulsed signals. All obtained scalograms have been averaged over the nighttime interval from 01h to 05h JST and flattened by means of multiplication by square of frequency. The sequence of spectra thus obtained has been compared with the evolution of seismicity, which has resulted in that the radiation in the vertical component has been detected. It exhibits seasonal variations with winter maxima, but it increases further by approaching the moment of the EQ and decreases after that. This radiation seems to be correlated with atmospheric parameters – air humidity, temperature, vapor pressure and rainfall. So, we consider that this radiation cannot be caused by subsurface sources, but its possible sources can be atmospheric discharges. The evolution of this phenome...

Source: Physics and Chemistry of the Earth, Parts ABC - March 10, 2015 Category: Science Source Type: research